• State TI Thinks Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 1 answer
  • Subscribers 34 subscribers
  • Views 645 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

HD3SS6126: Configuration of USB passive switch

RATHEESH V S
Prodigy 120 points
Part Number: HD3SS6126

Hi Please see the below configuration that I wish to use the USB passive switch.I wish to connect two USB port of a host  PC to two inputs of the first HD3SS6126  and another two USB port of same host PC to the inputs of second HD3SS6126 .The common outputs of the two USB switches is conncted to the two inputs of  third HD3SS6126.The output common terminal is connected to a USB flash drive.

Is the configuration works and if you could please let me know if any decrease in data transfer rate will occur.

Another Query

1.

What is the default impedance state (High/Low ) of the out put pins of HD3SS6126 .It is required to know the state to ensure the attached interconnection sequence(see the second image).

  • 0
    TI__Guru**** 176891 points

    Do you plan to have connector on both the input and the output of the HD3SS6126? 

    The HD3SS6126 is passive switch, if you plan to have connector on both the input and the output and max length cable is connected at both the input and output side, then the total cable length will exceed USB-IF max cable length requirement. It is best to have plug at the input or the output side so the max cable length requirement is not violated.

    Even with a plug at the input or the output side, you may still need a re-driver at the output of the HD3SS216 to compensate the loss from cascading two HD3SS6126 plus the board trace.

    Thanks

    David

  • 0
    TI__Guru*** 145550 points

    1: picture 1 should work. if trace too long, USB3 may drop to USB2, so it's better to have USB3 redriver after 3rd 6126.

    2: the impedance state is depending on what USB state is. In normal USB data transfer, USB3 will be 50ohm single ended, USB2 HS is 45ohm single ended.

    3: can you explain more for picture 2 what are you going to do?

  • 0 in reply to David (ASIC) Liu
    Prodigy 120 points

    Hi David,

    Thanks for the reply.

    I am planning to connect a USB extension cable(3 m) from a DUT'S USB port to the the input of the  HD3SS6126 and the output is connected to a USB pen drive/Flash drive.

    Ok I should connect a USB 3.0 redriver at the output of 3rd HD3SS216.

    Also I asked about as the pin impedance details of output terminals of HD3SS216 for the figure 2 .

    For figure 2 I wish to connect all the outputs of six  HD3SS216 and terminated to a single connector for connecting a USB pen drive/Flash drive.

    the inputs of all (six) HD3SS216 is conncted to USB connectors of six DUT's via cable .At a time only one DUT's USB connection is enabled.I could n't see any internal pull up /Pull down in the pin description of HD3SS216. Hope you got my circuit scenario.

  • 0 in reply to Brian Zhou
    Prodigy 120 points

    Hi Brain,

    Thanks for the reply.

    3: can you explain more for picture 2 what are you going to do?

     

    I wish to ON  /OFF  USB port of six DUTs via a control signal and at a time only pass  USB signals of one DUT to a USB Flash drive/Pen Drive.

    Scenario: 

    The inputs of all (six) HD3SS216 is conncted to USB connectors of six DUT's via USB  cable . The ON/OFF HD3SS216 is controls via a microcontroller. At a time only one DUT's USB connection is enabled.I could n't see any internal pull up /Pull down in the pin description of HD3SS216. Hope you got my circuit scenario.If I directly short the output terminals of six  HD3SS216 ,is any malfunction/Short circuit condition will occur when I switch one passive switch and the others are OFF.  

  • 0 in reply to RATHEESH V S
    TI__Guru**** 176891 points

    The HD3SS6126 is a FETS switch, the input/output is high Z when not being used, there is no internal pullup/pulldown.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 120 points

    Thanks David,

    Can I use the configuration of six HD3SS6126 shown as in the second image attached.

  • 0 in reply to RATHEESH V S
    TI__Guru**** 176891 points

    No, you can't share the USB3.0 bus as shown in the second image as it will create signal integrity issue.

    Thanks

    David